German Patent Publication (DE-PS) 2,636,521 discloses a known conveyor apparatus for powdered material. The known conveyor includes a turntable, a storage container arranged above the turntable, and several strippers of which a primary or coarse stripper produces a uniform layer thickness of powder on the turntable, and at least one further stripper strips or strikes the uniform layer of powdered material off the turntable. Such an arrangement has the disadvantage that it requires a coarse stripper and that the surplus material stripped off by the coarse stripper must somehow again be returned into the container. Further, the loose powder material could possibly flow from a pouring feed cone on the turntable directly to the final dosing stripper without having been stripped to the appropriate layer thickness by the first course stripper. Such a direct flow leads to non-uniformly dosed streams of loose powdered material.
European Patent Publication (EP-BL) 0,112,398 discloses another known apparatus for precisely dosing or feeding loose bulk materials by using dosing rollers having grooves machined in their surfaces and which rotate on a horizontally arranged shaft. In apparatus of the above type there is a danger or disadvantage that the loose bulk material may become too greatly compacted in the grooves of the dosing rollers or that the loose bulk material falls out of the grooves too early due to gravity. Such failures lead to a non-uniform discharge or feed stream of the material.
The known apparatus volumetrically dose or feed precisely the loose bulk material. However, known devices generally only operate with a relatively low output or conveying volumes which may, for example, only amount to a few grams per hour. turntable or rollers are driven at a constant rotational speed, whereby a single, non-adjustable output rate is provided.